Self-Organized Organic Semiconductors E-Book

Quan Li

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch
• Veröffentlichungsjahr: 2011

Seitenzahl: 487

Beschreibung

This book focuses on the exciting topic on self-organized organic semiconductors - from materials to device applications. It offers up-to-date and accessible coverage of self-organized semiconductors for organic chemistry, polymer science, liquid crystals, materials science, material engineering, electrical engineering, chemical engineering, optics, optic-electronics, nanotechnology and semiconductors. Chapters cover chemistry, physics, processing, and characterization. The applications include photovoltaics, light-emitting diodes (LEDs), and transistors.

Leseprobe

Table of Contents

Title Page

Copyright

Preface

Contributors

Chapter 1: Crystal Engineering Organic Semiconductors

1.1 INTRODUCTION

1.2 PACKING AND MOBILITY OF ORGANIC SEMICONDUCTORS

1.3 OVERCOMING THE PACKING PROBLEM

1.4 A MODULAR APPROACH TOWARD ENGINEERING π-STACKING

1.5 CONCLUSION

REFERENCES

Chapter 2: Conjugated Block Copolymers and Cooligomers

2.1 INTRODUCTION

2.2 CONJUGATED COPOLYMERS/COOLIGOMERS CONTAINING COIL AND ROD BLOCKS

2.3 CONJUGATED COPOLYMERS/COOLIGOMERS CONTAINING ALL-ROD BLOCKS

2.4 CONCLUSION

ACKNOWLEDGMENTS

REFERENCES

Chapter 3: Charge-Carrier Transport and Its Modeling in Liquid Crystals

3.1 INTRODUCTION

3.2 GENERAL FEATURES OF CARRIER TRANSPORT

3.3 CHARGE TRANSPORT MODEL FOR LIQUID CRYSTALS

3.4 CONCLUSION

REFERENCES

Chapter 4: Self-Organized Discotic Liquid Crystals as Novel Organic Semiconductors

4.1 INTRODUCTION

4.2 SEMICONDUCTING PROPERTIES OF DISCOTIC LIQUID CRYSTALS

4.3 DISCOTIC LIQUID CRYSTALS WITH HIGH CHARGE-CARRIER MOBILITY

4.4 PROCESSING OF DISCOTIC MATERIALS INTO ACTIVE SEMICONDUCTING LAYERS

4.5 APPLICATIONS OF SEMICONDUCTING DISCOTIC LIQUID CRYSTALS

4.6 CONCLUSION

ACKNOWLEDGMENTS

REFERENCES

Chapter 5: Self-Organized Semiconducting Smectic Liquid Crystals

5.1 INTRODUCTION

5.2 SMECTIC PHASES AND STRUCTURES

5.3 CHARACTERIZATION TECHNIQUES

5.4 Charge-Carrier Transport in Smectic Liquid Crystals

5.5 DEVICES AND APPLICATIONS

5.6 CONCLUSION AND OUTLOOK

ACKNOWLEDGMENTS

REFERENCES

Chapter 6: Self-Assembling of Carbon Nanotubes

6.1 INTRODUCTION

6.2 SELF-ASSEMBLING OF CNT BY VAN DER WAALS FORCES

6.3 SELF-ASSEMBLING OF CNT BY SPECIFIC CHEMICAL INTERACTIONS

6.4 SELF-ASSEMBLING OF CNT BY CHARGE TRANSFER INTERACTIONS

6.5 SELF-ASSEMBLING OF CNT BY DNA PAIRING

6.6 SELF-ASSEMBLING OF CNT BY ASYMMETRIC FUNCTIONALIZATION

6.7 CONCLUDING REMARKS

ACKNOWLEDGMENTS

REFERENCES

Chapter 7: Self-Organized Fullerene-Based Organic Semiconductors

7.1 INTRODUCTION

7.2 FULLERENE-BASED LIQUID CRYSTALLINE DONOR-ACCEPTOR BLENDS

7.3 FULLERENE-BASED LIQUID CRYSTALLINE COVALENTLY LINKED DONOR-ACCEPTOR DYADS

7.4 FULLERENE-BASED HYDROGEN-BONDED DONOR-ACCEPTOR ENSEMBLES

7.5 FULLERENE-BASED DONOR-ACCEPTOR BLENDS LINKED BY OTHER NONCOVALENT INTERACTIONS

7.6 FULLERENE-BASED SELF-ASSEMBLED MONOLAYERS

7.7 CONCLUSION AND OUTLOOK

ACKNOWLEDGMENTS

REFERENCES

Chapter 8: High-Efficiency Organic Solar Cells Using Self-Organized Materials

8.1 INTRODUCTION

8.2 SMALL-MOLECULE SOLAR CELLS

8.3 POLYMER SOLAR CELLS

8.4 CONCLUDING REMARKS

REFERENCES

Chapter 9: Selective Molecular Assembly for Bottom-Up Fabrication of Organic Thin-Film Transistors

9.1 INTRODUCTION

9.2 FABRICATION OF OFET ARRAY BY SURFACE-SELECTIVE DEPOSITION

9.3 IMPROVEMENT OF SELF-ORGANIZED OFET PERFORMANCE WITH AROMATIC SAM

9.4 FORMATION OF SINGLE-CRYSTAL OFET BY SURFACE-SELECTIVE DEPOSITION

9.5 FORMATION OF OFET ARRAY ON PLASTIC SUBSTRATE

9.6 EVALUATION OF VARIANCE IN CHARACTERISTICS OF SELF-ORGANIZED OFET

9.7 INVERTER CIRCUIT CONFIGURED FROM SELF-ORGANIZED OFET

9.8 ALL-SOLUTION-PROCESSED ASSEMBLY OF OFET ARRAYS

9.9 CONCLUSION

ACKNOWLEDGMENTS

REFERENCES

Color Inserts

Index

Copyright © 2010 by John Wiley & Sons, Inc. All rights reserved.

Published by John Wiley & Sons, Inc., Hoboken, New Jersey

Published simultaneously in Canada

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Library of Congress Cataloging-in-Publication Data:

Li, Quan, 1965-

Self-Organized organic semiconductors : from materials to device applications / edited by Quan Li.

p. cm. – (Wiley survival guides in engineering and science)

Includes index.

ISBN 978-0-470-55973-4 (hardback)

1. Organic semiconductors. 2. Self-assembly (Chemistry) 3. Self-Organizing systems.

TK7871.99.O74S45 2011

621.3815'2–dc22

2010036841

Preface

Organic semiconductors are attracting tremendous attention because of the promise of low cost and the possibility of roll-to-roll processing at ambient temperature and pressure. Among all organic semiconductors, self-organized organic semiconductors such as large π-conjugated liquid crystals and conjugated block copolymers undoubtedly represent a most exciting material today. The unique self-organized feature offers a brand new scientific frontier that holds immense opportunities as well as challenges in fundamental science that is opening the door for numerous applications such as organic photovoltaics, organic light-emitting diodes and organic field-effect transistors.

This book does not attempt to cover the whole field of self-organized organic semiconductors as this is extremely difficult to cover within a single book. Instead, the book focuses on the most fascinating topics in this field. Here self-organized organic semiconductors including crystal engineering organic semiconductors, conjugated block copolymers and cooligomers, charge transport and its modeling in liquid crystals, self-organized discotic liquid crystals, self-organized smectic liquid crystals, self-assembling of carbon nanotubes, and self-organized fullerene-based organic semiconductors are presented. The self-organized semiconducting materials, characterizations, and principles of devices are described. The applications of high-efficiency organic solar cells using self-organized materials and selective molecular assembly for bottom-up fabrication of organic thin-film transistors are also presented.

This book provides up-to-date and accessible coverage of self-organized semiconductors for graduate students and researchers in organic chemistry, polymer science, liquid crystals, materials science, material engineering, electrical engineering, chemical engineering, optics, optic-electronics, nanotechnology, and semiconductors. It can be used as a database and a reference by readers in both academia and industry. I sincerely hope that all those involved in research and education in this field will find the book to be useful.

Finally, I would like to express my gratitude to Jonathan Rose at John Wiley & Sons, Inc. for inviting us to bring this exciting field of research to a wider audience, and to all our distinguished contributors for their efforts. I am indebted to my wife Changshu and our two boys Daniel and Songqiao for their great support and encouragement.

Quan Li

June 18, 2010

Contributors

Liming Dai, Department of Chemical Engineering, Case School of Engineering, Case Western Reserve University, Cleveland, Ohio

Jun-ichi Hanna, Imaging Science and Engineering Laboratory, Tokyo Institute of Technology, Yokohama, Japan

Li-Mei Jin, Liquid Crystal Institute, Kent State University, Kent, Ohio

Masataka Kano, Dai Nippon Printing Co., Ltd., Kashiwa, Chiba, Japan

Paul A. Lane, U.S. Naval Research Laboratory, Washington DC

Quan Li, Liquid Crystal Institute, Kent State University, Kent, Ohio

Yongye Liang, Department of Chemistry and the James Franck Institute, The University of Chicago, Chicago, Illinois

Leonard R. MacGillivray, Department of Chemistry, University of Iowa, Iowa City, Iowa

Ji Ma, Liquid Crystal Institute, Kent State University, Kent, Ohio

Manoj Mathew, Liquid Crystal Institute, Kent State University, Kent, Ohio

Takeo Minari, MANA, NIMS, Tsukuba, Ibaraki, Japan; and RIKEN, Wako, Saitama, Japan

Akira Ohno, Imaging Science and Engineering Laboratory, Tokyo Institute of Technology, Yokohama, Japan

Anatoliy N. Sokolov, Department of Chemistry, University of Iowa, Iowa City, Iowa

Joseph C. Sumrak, Department of Chemistry, University of Iowa, Iowa City, Iowa

Kazuhito Tsukagoshi, MANA, NIMS, Tsukuba, Ibaraki, Japan; AIST, Tsukuba, Ibaraki, Japan; and CREST, JST, Kawaguchi, Saitama, Japan

Luping Yu, Department of Chemistry and the James Franck Institute, The University of Chicago, Chicago, Illinois

Chapter 1

Crystal Engineering Organic Semiconductors

Joseph C. Sumrak, Anatoliy N. Sokolov, and Leonard R. MacGillivray

Department of Chemistry, University of Iowa, Iowa City, Iowa

1.1 INTRODUCTION

Organic semiconductors are of great interest owing to the promise of low-cost flexible electronics (e.g., RFID tags, displays, e-paper) (1, 2, 3). A variety of conjugated organic polymers and oligomers have been synthesized and studied as semiconductors (4). Research has demonstrated semiconductors based on oligoacenes or oligothiophenes to be some of the most promising candidates for organic electronics. Pentacene has been one of the most widely studied organic semiconductors and has set a benchmark with room temperature mobilities as high as 35 cm2V−1s−1 for ultrapure single crystals (5). Oligomers, compared to polymer counterparts, offer samples of high purity and well-defined structure. While both polymer- and oligomer-based materials have been extensively studied for electronics application, the materials show varying mechanisms for charge transport. In oligomers charge-hopping between overlapping wavefunctions of nearest neighboring π-faces dominates the transport mechanism, while intrachain transport is observed in polymeric materials. Thus, the packing of small molecules in the solid state plays a key role in the charge transport properties (6). In this chapter, we discuss the influence of solid-state packing and the effects of recent attempts to establish control over the placement of molecules on the electronic properties of organic semiconductor solids.

A prerequisite for a molecule to function as an organic semiconductor is the presence of an extended π-conjugated surface. The extended packing of these molecules within single crystals or thin films establishes a degree of overlap between neighboring π-faces, which is characterized as the transfer integral. The extent of the overlap plays a great role in the increase of the ease of charge transport within a solid, or charge-carrier mobility. Indeed, studies have shown that cofacial stacking can lead to higher mobilities owing to increased orbital-orbital overlap between neighboring molecules (6, 7). However, the π-surfaces of most commonly used organic semiconductors (i.e., pentacene and oligothiophene) tend to crystallize in a herringbone, or edge-to-face, motif. Edge-to-face packing is nonideal to achieve maximum performance of an organic semiconductor owing to poor orbital overlap. Thus it is of great value to establish control of π-orbital overlap within semiconductor solids.

Crystal engineering is the use of intermolecular interactions to assemble molecules into a specific solid-state arrangement to achieve desired physical and chemical properties (8). Examples of such intermolecular forces include lipophilic, dipolar, and quadrupole interactions, as well as hydrogen bonding. Control of dimensionality in the solid state with noncovalent bonds has been realized through the formation of zero-dimensional (0-D), 1-D, 2-D, and 3-D assemblies (8). Recently, great interest has developed in the utilization of crystal engineering as a bottom-up approach to achieve increased overlap of molecular orbitals between neighboring semiconductor molecules. Improvement in the control of intermolecular interactions could also be used to stabilize the lattice of the transport media, resulting in increased maximum charge-carrier mobilities (9).

With these ideas in mind, this chapter discusses crystal engineering strategies in the context of semiconductor solids. It is first important to understand the nature of the structural problem that essentially plagues oligomer-based semiconductors (i.e., crystal packing). From there, strategies are described that utilize a range of interactions from steric crowding to circumvent edge-to-face packing to attractive forces (e.g., lipophilic) to enforce face-to-face geometries. We also describe a modular approach developed in our laboratory that achieves face-to-face stacking through hydrogen bonding in the form of molecular cocrystals. It should be noted that while the strategies described herein may be applicable for thin-film devices, the structure of a thin film will not necessarily correlate to that of a single crystal (10).